Reinforcement assemblages with monofilaments of liquid crystal organic polymers

ABSTRACT

A reinforcement assemblage formed at least in part of continuous monofilaments of liquid crystal organic polymer or polymers, characterized by the following features: 
     (a) the diameter D m  of the monofilaments is at least equal to 40 μm and less than 400 μm; 
     (b) the tenacity T a  of the assemblage is greater than 80 cN/tex; 
     (c) the secant tensile modulus M a  of the assemblage is greater than 2000 cN/tex; 
     (d) at least one of the monofilaments is practically wound helically around an axis, the acute angle γ which each monofilament makes with this axis, which is assumed rectilinear, being less than 30°; 
     (e) the twist of each monofilament on itself is less than 10 turns per meter of assemblage. 
     Articles reinforced by these assemblages, in particular automobile tires.

BACKGROUND OF THE INVENTION

The present invention relates to reinforcement assemblages formed atleast in part of monofilaments of organic material, these assemblagesbeing used to reinforce articles of plastic and/or rubber, particularlyautomobile tires.

French Patent 1,495,730 and U.S. Pat. No. 3,638,706 describereinforcement assemblages made with conventional monofilaments offlexible polymers, the diameters of these monofilaments being greaterthan 100 μm. These assemblages have low tenacities and tensile moduli.

It is known to use reinforcement assemblages formed of plied yarns ofmulti-filaments of liquid crystal organic polymers, for instance aramidmulti-filaments, the diameter of each elementary filament being small,on the order of 13 μm. These assemblages have high tenacities, but theirtensile modulus is definitely less than that of the initialmulti-filaments.

Japanese Patent Application JP-A-58-43802 describes the use, in thecrown of an automobile tire, of monofilaments, possibly twistedtogether, which monofilaments may be made of aromatic polyamides. Saidapplication does not give any information with regard to the mechanicalproperties of these monofilaments or of the assemblages which they form.

International Application PCT/CH90/00155, corresponding to U.S. Pat. No.5,246,776, incorporated herein by reference describes aramidmonofilaments having very high moduli and tenacities. Said applicationbriefly mentions the possibility of using these monofilaments inreinforcement assemblages, but without giving any information as to thestructure or properties of these assemblages.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to propose areinforcement assemblage with monofilaments of liquid crystal organicpolymer or polymers, said assemblage having very high tenacities andtensile moduli.

Therefore, the reinforcement assemblage in accordance with theinvention, formed at least in part of continuous monofilaments of liquidcrystal organic polymer or polymers, is characterized by the followingfeatures:

(a) the diameter D_(m) of the monofilaments is at least equal to 40 μmand less than 400 μm;

(b) the tenacity T_(a) of the assemblage is greater than 80 cN/tex;

(c) the secant tensile modulus M_(a) of the assemblage is greater than2000 cN/tex;

(d) at least one of the monofilaments is practically wound in a helixaround an axis, the acute angle γ which each monofilament makes withsaid axis, which is assumed rectilinear, being less than 30°;

(e) the twist of each monofilament on itself is less than 10 turns permeter of assemblage.

The invention also concerns articles reinforced by these assemblages, inparticular automobile tires.

DESCRIPTION OF THE DRAWING

The invention will be readily understood on basis of the non-limitativeexamples which follow and the diagrammatic figure relating to theseexamples, said figure being a section through a tire.

DESCRIPTION OF PREFERRED EMBODIMENTS

For simplicity in description, in the following text the term"monofilament" designates only monofilaments of a diameter at leastequal to 40 μm, and the term "filament" designates only monofilamentsthe diameter of which is less than 40 μm. The term "yarn" is used for anassembly of several continuous filaments, said assemblages beingpractically without twist. The term "product" designates a monofilament,a yarn or a textile assemblage.

By "liquid crystal polymer", there is understood herein, in knownmanner, a polymer capable of giving an optically anisotropic spinningcomposition in the molten state and at rest, that is to say in theabsence of dynamic stress, whether the polymer itself is in the moltenstate (in which case it is called "thermotropic") or in solution (inwhich case it is called "lyotropic"). Such a composition depolarizeslight when observed through a microscope between crossed linearpolarizers.

The invention will be illustrated by the following examples, theseexamples being produced, unless otherwise indicated, with aramidfilaments or monofilaments.

I. Determination of the Properties

1. Conditioning

By conditioning, there is understood in the present specification thetreatment of the products in accordance with German Federal Standard DIN53 802-20/65 of July 1979.

2. Titer

The titer of the products is determined in accordance with FederalGerman Standard DIN 53 830 of June 1965, these products having beenpreviously subjected to conditioning.

The measurement is effected by weighing at least three samples, eachcorresponding to a length of 50 m in the case of a monofilament or ayarn, or to a length of 5 m in the case of an assemblage. The titer isexpressed in tex. It is indicated as (Ti)_(m) in the case ofmonofilaments and (Ti)_(a) in the case of assemblages.

3. Diameter

The diameter of the monofilaments is determined by calculation from thetiter of the monofilaments and their density, in accordance with theformula:

    D.sub.m =2×10.sup.1.5 [(Ti).sub.m /πρ].sup.1/2

D_(m) representing the diameter of the monofilaments in μm, (Ti)_(m)representing the titer in tex, and ρ representing the density in g/cm³.

The diameter D_(a) of the textile assemblages is measured in accordancewith the following method. The assemblage is under tension; this tensionis between 0.9 and 1.1 times the standard pretension, which is 0.5cN/tex. The assemblage intersects a parallel beam of light. The shadowcast on a bar of photo-receiving diodes is measured instantaneously. Theresult of a measurement is the average width of the shadow, determinedat 900 points on 50 cm of assemblage. The diameter D_(a) of theassemblage is calculated by taking the average of four measurements, andit is expressed in μm.

4. Dynamometric Properties

The dynamometric properties of the products are measured by means of atraction machine of Zwick GmbH & Co (Federal Republic of Germany) oftype 1435 or 1445, corresponding to Federal German Standards DIN 51 220of October 1976, DIN 51 221 of August 1976, and DIN 51 223 of December1977, in accordance with the manner of procedure described in FederalGerman Standard DIN 53 834 of February 1976. The products are subjectedto traction over an initial length of 400 mm. In the case of the yarns,the measurements are carried out after they have been imparted apreliminary protective twist of 100 turns per meter.

In this way, the following properties are determined: tenacity, initialmodulus M_(i), secant modulus M_(a), elongation upon rupture. Thetenacity and the tensile moduli Mi_(i), M_(a) are expressed in cN/tex(centinewton per tex). The elongation upon rupture is expressed in %.

The tenacity is measured for all the products; it is indicated as T_(m)for the monofilaments and T_(a) for the textile assemblages.

The initial modulus M_(i) is defined as the slope of the linear part ofthe stress-strain curve which is present just after the standardpretension of 0.5 cN/tex. This modulus M_(i) is measured for themonofilaments and the yarns.

The secant modulus M_(a) is calculated for the assemblages in accordancewith the relationship: ##EQU1## in which F_(i) is the force to which theassemblage is subjected for an elongation of 0.35%; F₂ is the force towhich the assemblage is subjected for an elongation of 0.10%.

The elongation upon rupture is determined for all the products. It isdesignated (Ar)_(m) for the monofilaments and (Ar)_(a) for theassemblages.

All the dynamometric properties are determined by taking the average often measurements.

5. Density

The densities ρ of the monofilaments are measured using the densitygradient tube technique for plastics which is specified in ASTM StandardD1505-68 (reapproved in 1975), Method C, using a mixture of1,1,2-trichlorotrifluoroethane and 1,1,1-trichloroethane as liquidsystem for the density gradient tube.

The samples used are short lengths of about 2 cm of monofilaments,knotted but not closely. Before measurement, they are immersed for twohours in the component of the liquid system which has the lowestdensity. They then remain in said tube for 12 hours before beingevaluated. It is particularly seen to it that no air bubbles areretained on the surface of the monofilaments.

The density is determined in g/cm³ for 2 samples per monofilament, andthe average value is reported to 4 significant places.

6. Inherent Viscosity

The inherent viscosity (I.V.) of the polymer is expressed in deciliterper gram and defined by the equation:

    I.V.=(1/C) Ln (t1/to)

in which

C is the concentration of the polymer solution (0.5 g of polymer in 100cc of solvent,

The solvent is 96% concentrated sulfuric acid.

Ln is the natural logarithm.

t1 and to represent the flow time of the polymer solution and of thepure solvent, respectively at 30±0.1° C. in an Ubbelohde type capillaryviscosimeter.

7. Optical Properties

The optical anisotropy of the spinning compositions, in the molten stateat rest, is observed by means of a polarization microscope of OlympusBH2 type, equipped with a heating stage.

II. Production of the Monofilaments

The aramid monofilaments are prepared by the method claimed inApplication PCT/CH90/00155 mentioned above. The essential points of thispreparation are as follows:

(a) a solution is used of at least one aromatic polyamide such that atleast 85% of the amide linkages (--CO--NH--) are joined attacheddirectly to two aromatic rings, the inherent viscosity of this polyamideor these polyamides being at least equal to 4.5 dl/g, the concentrationof the polyamide or polyamides in the solution being at least 20% byweight, this spinning composition being optically anisotropic in themolten state and at rest;

(b) this solution is extruded in a spinneret through a capillary thediameter of which is greater than 80 μm, the spinning temperature, thatis to say the temperature of the solution upon its passage through thecapillary being at most equal to 105° C.;

(c) the liquid jet emerging from the capillary is drawn in a layer ofnoncoagulating fluid;

(d) the drawn liquid vein thus obtained is introduced into a coagulatingmedium, the monofilament which is thus undergoing formation remaining indynamic contact with the coagulating medium for the time "t", thetemperature of the coagulating medium being at most equal to 16° C;

(e) the monofilament is washed and dried; the diameter D_(m) of the drymonofilament which has thus been completed and the time t are related bythe following relationships:

    t=KD.sup.m.sup.2 ; K>30

t being expressed in seconds and D_(m) being expressed in millimeters.

The monofilaments prepared by this method satisfy each of the followingrelationships:

1.7≦(Ti)_(m) <180;

40≦D_(m) <400;

T_(m) ≧170-D_(m) /3;

Mi>2000;

(Ti)_(m) being the titer in tex, D_(m) being the diameter in μm(micrometers), T_(m) being the tenacity in cN/tex, Mi being the initialmodulus in cN/tex for this monofilament.

Various additives or substances such as, for instance, plasticizers,lubricants, and products for improving the adhesiveness of the productto a rubber matrix can possibly be incorporated in the polymer or thespinning solution or applied to the surface of the monofilament duringthe different steps of the method previously described.

III. Examples of Production and/or Use of Assemblages

Three automobile tires are used of size 135/70-13. One of these tires isin accordance with the invention while the other two are control tires.The figure diagrammatically shows the tire in accordance with theinvention. This tire 10 has a crown 1, two sidewalls 2 and two beads 3each reinforced by a bead ring 4. A radial carcass ply 5 is arrangedfrom one bead 3 to the other, being turned up around the bead rings 4.The crown 1 is reinforced by a reinforcement 6. These three tires areidentical except with respect to the crown reinforcement 6, which ismade in the following manner:

Tire in accordance with the invention

It is reinforced by assemblages in accordance with the invention whichhave the formula (1+6)18, that is to say a formula of the layer cabletype with one monofilament serving as core and six monofilaments woundin a helix around this core so as to form a layer, the diameter of themonofilaments being about 0.18 mm (180 μm). The monofilaments are ofpoly(p-phenylene terephthalamide), and they are prepared in accordancewith Chapter II.

The average properties of the monofilaments are as follows:

(Ti)_(m) : 36.4 tex

D_(m) : 180 μm

T_(m) : 149 cN/tex

Mi: 5300 cN/tex

(Ar)_(m) : 3.7%

ρ: 1.43 g/cm³

The properties of the assemblage are as follows:

γ: 6 degrees

(Ti)_(a) : 258 tex

D_(a) : 540 μm

T_(a) : 140 cN/tex

M_(a) : 4600 cN/tex

(Ar)_(a) : 3.9%

The angle γ of 6° corresponds to the acute angle which the sixmonofilaments of the layer make with the axis of the assemblage, themonofilament forming the core being oriented along said axis andtherefore with an angle γ of zero or practically zero, its twist onitself being practically zero.

The twist of each monofilament on itself in the layer of the assemblageis less than 10 turns per meter of assemblage. Two superposed plies areused. Each ply comprises assemblages arranged parallel to each otherwith a distance of 0.8 mm between two adjacent assemblages, measuredfrom axis-to-axis.

In each ply the assemblages form an angle of 22 degrees with theequatorial plane of the tire 10, represented by the line yy' in thefigure, these plies being crossed with respect to this equatorial plane.

Tire not in accord with the inventions, with steel wires

The crown reinforcement 6 comprises two plies, each reinforced withmetal cables of formula 6/23. Each of these cables is formed of threestrands wound together, each of these strands being formed of two wireswhich are wound together. The assemblage pitch is 12.5 mm, as is thepitch of each strand. The helical winding of the wires of a strand iseffected in a direction opposite that of the winding of the wires of theother two strands. Each wire is of brass-coated steel and has a diameterof 0.23 mm, a resistance to rupture of 2886 MPa, and an elongation uponrupture of 2.4%. Each cable has a diameter of 0.77 mm, a resistance torupture of 2760 MPa, a tensile modulus of elasticity of 195 GPa and anelongation upon rupture of 2.1%. These mechanical properties are definedin accordance with ASTM Standard D-2969.

In each ply the steel cables form an angle of 22 degrees with theequatorial plane yy' of the tire 10, these plies being crossed withrespect to said equatorial plane, the cables of any one ply beingparallel to each other, that is to say the general arrangement of theplies is the same for the tire of the invention and for this controltire. The axis-to-axis distance between two adjacent steel cables is 1.7mm.

Tire not in accord with the invention, with plied yarns of aramids

The crown reinforcement 6 comprises two plies, each reinforced withplied yarns of KEVLAR® 29 type 950 of du Pont de Nemours, of formula167x2. Each of these plied yarns is formed of two yarns of 167 tex each,twisted individually to 315 turns per meter and twisted together inopposite direction to 315 turns per meter. The characteristics of thistype of yarn are a tenacity of 185 cN/tex, an elongation upon rupture of3.6%, and an initial modulus of 4900 cN/tex. The properties of the pliedyarn produced are a tenacity of 150 cN/tex, an elongation upon ruptureof 5.1%, and a secant modulus of 1950 cN/tex.

The general arrangement of the plies is the same as for the tirespreviously described. The axis-to-axis distance between two plied yarnsin this case is 1.25 mm.

Each of the plies, whether or not in accord with the invention, has aresistance to rupture in traction of about 4000 N per cm of width, thisresistance being measured parallel to the axes of the assemblages of theply, the center-to-center distance previously mentioned, as well as thewidth being measured perpendicular to these axes.

The assemblages of the invention, before incorporation in the rubber,have undergone the following treatment.

These assemblages are placed in contact with a plasma for about 30minutes, the conditions of this treatment being:

plasma gas: oxygen,

pressure of the gas: 20 Pa (150 millitorrs),

power of the apparatus: 2.5 kW.

The assemblages, after the plasma treatment, pass into a first epoxyresin bath; they experience a heat treatment between 210° and 260° C.for a period of time of between 20 and 120 seconds, for instance 250° C.for 30 seconds. They are then passed into a second bath having a base ofbutadiene/styrene/vinylpyridine terpolymer latex, resorcinol andformaldehyde, and they undergo a heat treatment between 210° and 260° C.for a period of time of between 20 and 120 seconds, for instance 250° C.for 30 seconds.

In the control tire with aramid plied yarns, the plied yarns, beforeincorporation in the rubber, are subjected to the same double-bathtreatment as the assemblages in accordance with the invention, butwithout prior plasma treatment.

The rubber of the reinforcements 6 is the same for all three tires, thisrubber being of known type.

The weights of the tires are as follows: control tire with steel wires(A): 4.36 kg; tire according to the invention (B): 4.06 kg; control tirewith plied yarns (C): 3.94 kg.

The three said tires are subjected to the following tests:

(1) Drift thrust

Each tire is mounted on a 4.00 J 13 wheel and subjected to a load of 315daN and inflated to 2.2 bars. It is rotated at a speed of 40 km/h on arotor wheel of a circumference of 8.5 m. The angle of drift is variedand the drift thrust is measured in known manner by measuring thetransverse force on the wheel for each of these angles.

The results are set forth in table 1.

                  TABLE 1                                                         ______________________________________                                        Drift thrust (daN)                                                            Thrust Angles (degrees)                                                       Tire    1      2        3    4      5    6                                    ______________________________________                                        A       66.7   125.8    174.3                                                                              212.9  237.5                                                                              251.2                                B       64.2   122.6    171.9                                                                              210.4  233.8                                                                              247.8                                C       62.9   118.2    158.5                                                                              188.0  210.0                                                                              226.3                                ______________________________________                                         A: control tire with steel wires                                              B: tire in accordance with the invention                                      C: control tire with plied yarns                                         

It is therefore seen that the tire of the invention has a behavior verysimilar to that of the control tire with steel wires which is not inaccord with the invention, but very different from the tire having atextile belt of aramid plied yarns, also not in accord with theinvention, the drift thrust of which is much less.

(2) Resistance to rolling

Each tire is mounted on a 4.00 J 13 wheel, inflated to 2.2 bars, andsubjected to a load of 315 daN. The resistance to rolling is measured asa function of the speed of rolling of the tire on a rotor wheel thecircumference of which is 8.5 m. The resistance to rolling is defined asbeing the ratio between the force opposing the rolling, expressed indaN, and the load applied on the tire, expressed in tons.

The results are given in table 2.

                  TABLE 2                                                         ______________________________________                                        Resistance to rolling (daN/t)                                                 Speeds (km/hr)                                                                Tire    60     80       100  120    140  160                                  ______________________________________                                        A       11.19  11.50    12.11                                                                              13.17  15.60                                                                              19.26                                B       11.08  11.48    12.06                                                                              13.18  15.57                                                                              19.35                                C       11.28  11.30    12.05                                                                              12.95  15.08                                                                              18.68                                ______________________________________                                         A: control tire with steel wires                                              B: tire according to the invention                                            C: control tire with plied yarns                                         

It is therefore seen that the three tires have practically the samebehavior.

(3) Crown impacts

Each tire is mounted on a 4.00 J 13 wheel and is inflated to 2.2 bars. Ahemispherical indentor, guided in vertical translation, is caused tofall from a variable height onto the crown of each tire, the impacttaking place at the center of the tread. The energy necessary to piercethe two belt plies of each tire is determined. The results are set forthin table 3.

                  TABLE 3                                                         ______________________________________                                        Crown impacts                                                                 Tire      Energy of Rupture (Nm)                                              ______________________________________                                        A         223                                                                 B         264                                                                 C         >314                                                                ______________________________________                                         A: control tire with steel wires                                              B: tire in accordance with the invention                                      C: control tire with plied yarns                                         

The tire of the invention (B) therefore has better resistance to impactsthan the control tire with steel wires (A), while the control tire withplied yarns (C) has the best resistance to impacts.

(4) Endurance

Each tire is mounted on a 4.00 J 13 wheel and inflated to 2 bars. It iscaused to roll on a rotor wheel of 22 m circumference at an averagespeed of 72 km/hr under a load of 320 dan with overload sequences and ondifferent types of coverings and obstacles which intentionally produceshears in the belt plies. The test is stopped at 40,000 km and it isnoted that the three tires do not at that time show any substantialdeterioration, that is to say they behave in equivalent fashion.

In conclusion, the tire according to the invention is lighter than thesteel wire tire, while having practically the same drift thrust, thesame resistance to rolling, the same endurance behavior, and betterresistance to perforation.

Furthermore, the tire of the invention has a far better drift thrustthan the control tire with plied yarns.

When the angle γ becomes equal to or greater than 30° and/or when thetwist of a monofilament on itself becomes equal to or greater than 10turns per meter, the tenacity T_(a) of the assemblage as well as itsmodulus M_(a) decrease excessively.

The assemblages of the invention are economically advantageous and canbe produced, whatever the architecture of the assemblages, on theexisting machines for the cabling of steel wires.

In the assemblage of the invention, we preferably have γ<20° and evenmore advantageously, γ<10°.

In the assemblage of the invention, there are preferably at least one ofthe following relationships:

    T.sub.a ≧110; M.sub.a ≧3000; (Ar).sub.a >3.

Advantageously, there is at least one of the following relationships:

    T.sub.a ≧140; M.sub.a ≧4000; (Ar).sub.a >3.5.

The monofilament used in the assemblage according to the inventionpreferably satisfies the previously mentioned relationships:

1.7≦(Ti)_(m) <180; T_(m) ≧170-D_(m) /3; Mi>2000, and it preferablysatisfies the relationship (Ar)_(m) >2.

When this monofilament is of aramid, it preferably satisfies thepreferred relationships given in Application PCT/CH90/00155 mentionedabove and, in particular, at least one of the following relationships:

    T.sub.m ≧190-D.sub.m /3; Mi≧6800-10 D.sub.m ; (Ar).sub.m >3.

In these relationships, the tenacities and moduli are expressed incN/tex, the elongations upon rupture in %, D_(m) is expressed in μm, and(Ti)_(m) is expressed in tex.

The preceding examples in accordance with the invention were producedwith monofilaments of poly(pphenylene terephthalamide) but one may useother aramid monofilaments in accordance with Application PCT/CH90/00155mentioned above or monofilaments other than aramids, for instancemonofilaments of aromatic polyesters. One may also use combinations ofmonofilaments formed of different polymers, for instance an assemblagecomprising aramid monofilaments and monofilaments of aromaticpolyesters.

The example which follows concerns an assemblage in accordance with theinvention consisting of aramid monofilaments other than poly(p-phenyleneterephthalamide).

These monofilaments are of aromatic copolyamide, this copolyamide beingobtained from the following monomers: terephthaloyl dichloride,paraphenylene diamine, 1,5-naphthylene diamine (NDA), with 3 mols of NDAto 100 mols of diamines, these monofilaments being in accord with theaforesaid Application PCT/CH90/00155.

The average characteristics of the monofilaments are as follows:

(Ti)_(m) : 36.3 tex

D_(m) : 180 μm

T_(m) : 121 cN/tex

Mi: 4570 cN/tex

(Ar)_(m) : 3.2%

ρ: 1.42 g/cm³

The properties of the assemblage are the following, this assemblagehaving the formula (1+6)18:

γ: 6 degrees

(Ti)_(a) : 257 tex

D_(a) : 540 μm

T_(a) : 109 cN/tex

M_(a) : 3820 cN/tex

(Ar)_(a) : 3.4%

All of these properties are determined in accordance with chapter Iabove, these monofilaments being produced in accordance with chapter IIabove.

The following example relates to an assemblage with monofilaments ofaromatic polyester.

These monofilaments are obtained by the melt spinning of a commercialaromatic polyester Vectra® of Hoechst Celanese, the temperature ofextrusion of the polymer being close to 340° C., through a capillary(diameter 800 μm) of a spinneret maintained at a temperature of 270° C.The liquid jet emerging from the spinneret is drawn in air (draw ratioequal to 19.8) and is solidified by passage through a heat quenchingzone.

The monofilament thus obtained is taken up on a winding device at aspeed of 590 m/min in order to be subjected then to apost-polycondensation heat treatment on the receiving bobbin. Thistreatment is carried out in accordance with different temperature stagesof between 220° and 260° C. and a final step of 16 hours at 270° C.

The monofilaments thus spun and treated have the following averageproperties:

(Ti)_(m) : 36.4 tex

D_(m) : 182 μm

T_(m) : 131 cN/tex

Mi: 4300 cN/tex

(Ar)_(m) : 2.5%

ρ: 1.40 g/cm³

The properties of the assemblage are the following, this assemblagehaving the formula (1+6)18:

γ: 6 degrees

(Ti)_(a) : 258 tex

D_(a) : 545 μm

T_(a) : 112 cN/tex

M_(a) : 3800 cN/tex

(Ar)_(a) : 2.5%

All these properties are determined in accordance with chapter I above.

The examples in accordance with the invention which have been previouslydescribed were produced completely with continuous monofilaments ofliquid crystal polymers, but the invention applies to cases in which theassemblages comprise other components than such monofilaments, forinstance rubbers or plastic resins forming a core or at least partiallyimpregnating these monofilaments, or reinforcement elements formed ofstaple fibers or of inorganic or metallic threads.

Of course, the invention is not limited to the embodiments describedabove. Thus, for instance, it applies to assemblages other than those offormula (1+6), the assemblages of the invention being preferably of the"layer cable" type (saturated or unsaturated layers), for instance offormula (3+8), with three monofilaments cabled together serving as coreand a layer of eight monofilaments wound around this core, theseassemblages possibly comprising several layers of monofilaments.

The assemblages in accordance with the invention can be produced byknown methods and with known devices. These methods and devices which,for purposes of simplification have not been described, can, forinstance, be cabling methods and devices similar to those used toproduce assemblages with metal wires, in such a manner that the twistingof the monofilaments on themselves is less than 10 twists per meter ofassemblage.

We claim:
 1. A reinforcement assemblage formed at least in part ofcontinuous monofilaments of liquid crystal organic polymer or polymers,characterized by the following features:(a) the diameter D_(m) of themonofilaments is at least equal to 40 μm and less than 400 μm; (b) thetenacity T_(a) of the assemblage is greater than 80 cN/tex; (c) thesecant tensile modulus M_(a) of the assemblage is greater than 2000cN/tex; (d) at least one of the monofilaments is wound helically aroundan axis of the assemblage, the acute angle γ which each monofilamentmakes with this axis, being less than 30°; (e) the twist of eachmonofilament on itself is less than 10 turns per meter of assemblage. 2.An assemblage according to claim 1, wherein the angle γ is less than20°.
 3. An assemblage according to claim 2, the angle γ is less than10°.
 4. An assemblage according to claim 1, wherein said assemblagesatisfies at least one of the following relationships:

    T.sub.a ≧110; M.sub.a ≧3000; (Ar).sub.a >3;

(Ar)_(a) being the elongation upon rupture of the assemblage, expressedin %.
 5. An assemblage according to claim 4, wherein said assemblagesatisfies at least one of the following relationships:

    T.sub.a ≧140; M.sub.a ≧4000; (Ar).sub.a >3.5.


6. An assemblage according to claim 1, wherein at least one of themonofilaments satisfies the relationships:1.7≦(Ti)_(m) <180; T_(m)≧170-D_(m) /3; Mi>2000;(Ti)_(m) being the titer of the monofilamentexpressed in tex, T_(m) being the tenacity of the monofilament expressedin cN/tex, Mi being the initial modulus of the monofilament expressed incN/tex, and D_(m) being expressed in μm.
 7. An assemblage according toclaim 6, wherein the monofilament is an aramid monofilament.
 8. Anassemblage according to claim 6, wherein the monofilament satisfies thefollowing relationship:

    (Ar).sub.m >2

(Ar)_(m) being the elongation upon rupture of the monofilament.
 9. Anassemblage according to claim 8, wherein the monofilament consists of anaramid and satisfies at least one of the following relationships:

    T.sub.m ≧190-D.sub.m /3; Mi≧6800-10D.sub.m ; (Ar).sub.m >3.


10. An assemblage according to claim 9, wherein the monofilamentconsists of poly(p-phenylene terephthalamide).
 11. An assemblageaccording to claim 1, wherein said assemblage has a layer cablestructure.
 12. An assemblage according to claim 1, wherein saidassemblage is at least partially impregnated with rubber or a plasticresin.
 13. An article reinforced by at least one assemblage according toclaim
 1. 14. An article according to claim 13, wherein said assemblageis an automobile tire.
 15. An automobile tire according to claim 14,wherein the assemblage is used to reinforce the crown of the tire.